Active Thermal Cooling Technologies - Low Energy Cooling for Sustainable Buildings - page 117

Table 5.2 Performance of ammonia/water absorption chillers and diffusion-absorption
machines with auxiliary gas

Cycle type SE DL SE

Auxiliary gas — — hydrogen/helium

Cold temperature / ◦ C − 30-20 − 50-20 − 20-20

Heating temperature / ◦ C 90-160 55-65 100-140

Cooling water temperature / ◦ C 30-50 30-35 30-50

COP 0.4-0.6 0.4 0.2-0.5

driving heat temperatures. The COP of those chillers with auxiliary gas is even lower,
between 0.2 and 0.5.

5.1.2 Solar Cooling with Absorption Chillers

In the 1970s, the American company Arkla Industries Inc., (now owned by Robur SpA,
Italy) developed the first commercial, indirectly driven, single effect H 2 O/LiBr ACM
for solar cooling with two different nominal cooling capacities. One was the 3-TR
Solaire or Solaire 36 unit with a 10 kW cooling capacity and the other Solaire unit had
a 75 kWcooling capacity. The driving heat temperatures were in the range of 90 ◦ C and
the cooling water temperature was 29 ◦ C for 7 ◦ C cold water temperature. The machine
was installed in more than 100 demonstration projects in the USA (Loewer, 1978;
Lamp and Ziegler., 1997; Grossmann, 2002). Arkla and also Carrier Corp., USA, then
developed a small-size single effect H 2 O/LiBr ACM that could work with air cooling.
There was no market success, mainly because of the high investment costs for solar
cooling. Carrier Corp. further decreased the driving temperature of a water-cooled
single effect H 2 O/LiBr ACM by using a falling film generator with a large surface

2

1.8

1.6 Carnot process 3-effect

1.4

1.2

2-effect

1

0.8

Chilled water: 7.0 o C
Cooling water: 30.0 o C

1-effect

0.6

0.4

0.2

0

50 100 150 200 250

Heat supply temperature / o C

Figure 5.5 COP as a function of the heat input temperature for different water/lithium bromide
absorption cycles (Grossmann, 2002)